The present invention relates to a device for grasping load structures and more particularly, to a device for grasping utility sections such as the castings and riser rings used in municipal drains while they are being lifted, moved or lowered.
Many construction projects involving municipal storm and sewer drains require the setting of iron castings above manholes. In setting a casting, workers must ensure that the casting is properly graded with the ground surface. As such, workers adjust the elevation of the casting by placing a concrete riser ring of appropriate height, typically between four and twelve inches, in order to grade the casting.
Because riser rings and castings generally weigh between 100 and 500 pounds, it is desirable to lift such load structures using a lifting device such as an overhead crane or the like. Traditionally, workers would use chains to rig the load structure to the lifting device.
There are many drawbacks associated with using chains and similar grasping devices to lift or move drain sections such as castings and riser rings. While the lifting equipment provides the lifting force, many of the tasks in setting the load structure require manual force. For example, in using chains, the load structure may tilt off the level plane making it difficult to accurately position the load structure as it is being lowered. In this scenario, manual force is required to slide the load structure into the correct position. This is also dangerous because the worker who manually moves the load structure risks serious injury if the load structure become unstable and falls.
Further, previous grasping devices, such as chains, grasp the load structure from the inside, thereby requiring workers to step inside the load structure and manually lift it to remove the chains once the load structure has been lowered. Therefore, the problems associated with using traditional grasping devices, such as chains, can lead to fatigue and injury and often requires the use of two or more workers.